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In situ and 3D environmental transmission electron microscopy of Pd-Al2O3 nano catalysts : Fast tomography with applications to other catalytic systems in operando conditions and to electron beam sensitive nanomaterials

Abstract : In the beginning of the XXIst century, Environmental Transmission Electron Microscopy has become one of the reliable characterization techniques of nanomaterials in conditions mimicking their real life. ETEM is now able to follow the dynamic evolution of nanomaterials under various conditions like high temperature, liquid or various gas pressures. Among various fields of research, catalysis can benefit significantly from Environmental Microscopy. This contribution starts with the study of the Palladium-Alumina catalytic system. Pd nanoparticles supported by α-Al2O3 and δ-Al2O3 are of an important physicochemical and environmental interest, particularly in the field of selective hydrogenation in petrochemistry, for the synthesis of polymers or CO2 hydrogenation for methane production. We first performed 2D analyses at different steps of the synthesis process, then the same synthesis steps were performed under in situ conditions. The motivation of this approach was to compare post mortem treatments with ETEM observations. In general, 2D data provide limited insights on, for example, the morphology and position of supported nanoparticles. We have then developed a new fast acquisition approach to collect tomographic tilt series in very short times, enabling to reconstruct nano-systems in 3D during their dynamical evolution. Taking advantage of this approach, we have determined the activation energy for soot combustion on YSZ oxidation catalysts for diesel motors from volumetric data extracted from in situ experiments. Fast electron tomography was also applied to electron beam sensitive materials, like polymer nanocomposites and biological materials, showing the wide spectrum of possible applications for rapid 3D characterization of nanomaterials.
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Submitted on : Tuesday, November 13, 2018 - 3:06:06 PM
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  • HAL Id : tel-01920885, version 1

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Siddardha Koneti. In situ and 3D environmental transmission electron microscopy of Pd-Al2O3 nano catalysts : Fast tomography with applications to other catalytic systems in operando conditions and to electron beam sensitive nanomaterials. Material chemistry. Université de Lyon, 2017. English. ⟨NNT : 2017LYSEI123⟩. ⟨tel-01920885⟩

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